1. Field of the Invention
The present invention relates to a multilayer filter including a plurality of dielectric layers stacked on each other and including electrode patterns provided thereon, and more particularly, to a multilayer filter including balanced output terminals.
2. Description of the Related Art
Previously, various types of multilayer circuit elements have been proposed in which predetermined circuit functions are realized by stacking a plurality of dielectric layers on which predetermined electrode patterns are formed. As one of those multilayer circuit elements, there is a multilayer filter for realizing a filter function. Further, there is a multilayer filter having the unbalanced-balanced transforming function (hereinafter referred to as a “multilayer balanced filter”), as disclosed in Japanese Unexamined Patent Application Publication No. 2005-45447.
In the multilayer balanced filter disclosed in Japanese Unexamined Patent Application Publication No. 2005-45447, a plurality of ½-wavelength resonators each opened at both ends are arranged to be electromagnetically coupled with each other. An unbalanced input terminal is connected to the ½-wavelength resonator at one end, and balanced output terminals are connected respectively to two terminals of the ½-wavelength resonator at the other end. Those plural ½-wavelength resonators are provided by inner layer electrodes that are formed in a laminate (multilayer body).
However, because the multilayer balanced filter disclosed in Japanese Unexamined Patent Application Publication No. 2005-45447 has such a structure that an inductor on the balanced output side is formed by the inner layer electrode and both ends of the inductor are directly connected to the balanced output terminals, it is not easy to set a phase balance between the balanced output terminals arranged in a pair to a desired value by utilizing the shape of the inner layer electrode, which forms the inductor, and a wiring pattern for the inner layer electrode.